The use of ham stock in soups etc is fairly standard. This seems to be an extension of that principle.
My favourite ham recipe is a ham and parsley terrine, in which smoked ham is simmered with carrot, onion, leek, celery and parsley stalks, allowed to cool and cut and torn into small chunks. These are mixed with mustard, a chopped raw shallot, some vinegar and quite a lot of chopped parsley and put in a terrine dish. One then strains and seasons the stock in which the ham was cooked, adds gelatine and pours over the ham mixture. This is allowed to set. It can be cut into slices to serve but the tricky bit is getting enough gelatine so it does not fall to pieces, without it becoming too rubbery. Best cut when cold from the fridge, but should be allowed to come to room temp before eating so the flavour can develop.
The French call it jambon persillée. But my recipe comes from an Italian recipe book.